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30 "THE MARINE. REVIEW SUBMARINES By Sir William H. White.* French official documents distinguish between submarine and submersibles, but there is no real difference of principle in. their respective design. Both classes are capable of entire submergence and under water propulsion. The distinction between them consists in the larger reserve of buoyancy and higher freeboard of the submersible type when floating at minimum draught. As a consequence the submersible type enjoys better conditions of propulsion and habitability when on the surface, while the amount of water which has to be admitted into tanks before submersibles are ready for diving, is necessarily greater than the corresponding admission for submarines. Many of the latter type are of relatively small dimensions, but some submarines are of large size and have been furnished with light forecastles and flying bridges for the purpose of securing both accommodation for their crews and assisting propulsion at the surface. It was anticipated, and, indeed, it seemed probable that the submarine type would gain upon the submersible in the time required to pass from the surface condition to the diving condition; and it was held that such a gain in rapidity of diving might be of great value on service. Trials made recently with repre- sentative vessels of the two types have, however, led to the conclusion that the submarine type does not gain sensibly, if at all, upon the submersible in this particular; whereas the submersible has been proved to be much superior in regard to surface-propulsion, maneuvering-power, and habitability. Two vessels were tried at Cherbourg in March last before a special commission, presided over by Admiral Philibert--the Aigrette (submersible type) and submarine Z. The Aigrette is a vessel about 118 ft. long and of 170 tons displacement, with engines of 200 H. P. and an estimated ' surface speed of about 10% knots. Submarine Z is about 136 ft. in length, of 200 tons displacement, with engines of 190 H. P. intended to secure a surface speed of 11 knots. A small forecastle was built at the forward end of Z to _ house the torpedoes and to assist propulsion, while a light flying bridge was added in order that the crew might obtain fresh air in the surface condition. Detailed reports of the trials have appeared in Le Yacht and elsewhere; from which the Aigrette appears to have been superior to her competitor in manettvering power, in steadiness, and in speed, much more comfortable for the crew, and more rapid: in preparation for diving. The superiority in behavior of the Aigrette is said to have increased as the wind and sea rose. As the result. of these trials it is anticipated that the sub- marine type will give place to the submersible type except for coast or harbor defense, wherein a small radius of action suffices. For offensive work, requiring a larger radius of action, the submersible type is considered necessary. French writers are of opinion that large submersible vessels might be employed in attacks on an enemy's coasts, both in the Northern Seas and in the Mediterranean; vessels of about 400 tons and 6oo H. P., attaining a surface speed of 12 knots, are regarded as satisfactorily fulfilling the requirements. Further, it is held that for harbor and coast defense, vessels of about I00 tons displacement should suffice. Besides these two types some authorities recommend the construction of a third type -of small submarines which could be lifted on board and carried by ships, much as second-class torpedo boats and vedette boats are carried in battleships and cruisers. Special lifting appliances must be provided, so that the sub- marines might be put afloat quickly in a condition ready for immediate service. The French have already dispatched some of their smaller submarines (about 77 ft. in length and 68 tons displacement) to Saigon in order that they might form part of the defense mobile, and no difficulty was experi- enced in their transport. A small experimental submarine *London Times Engineering Supplement. specially adapted for the service indicated is said to have been ordered in 1904, the length being about 36 ft. and the displacement 21 tons. The Goubet type of submarine was of very small size and was worked out successfully by its in- ventor; but it has not been officially approved or adopted by French naval authorities. It could have been readily carried on shipboard, being about 26 ft. long with a lifting weight of less than 10 tons; the speed was about 514 knots, and the radius of action 25 knots. Propulsion was by electrical power, and the armament consisted of locomotive torpedoes carried outside the vessel with suitable releasing gear. The trials of the Aigrette and submarine Z are said to have led to the suspension of the construction of proposed sub- marines of 420 tons displacement (Emeraude class), and of smaller submarines which M. Pelletan had ordered in amend- ment of his predecessor's programme for vessels of the Aigrette class. So far as these trials in France bear upon British construction there is every reason for congratulation. Our later vessels have all been of the submersible rather than of the submarine type; and their designs have been continuously improved on definite lines towards one general direction. Our B class of submarines are of 300 tons dis- placement and 850 H. P., with a surface speed of 13 knots and radius of 500 miles. Fresh supplies of gasoline can be readily obtained at sea from depot ships, These vessels, therefore, compare favorably with the future submersibles contemplated in France. As to the time required for diving, the British submarines take three minutes, which is less than the time occupied in the French trials. Obviously, it is a serious hindrance to real progress if the personal views of any individual who may temporarily occupy the post of Minister of Marine are allowed to interfere with well-con- sidered programmes of naval construction. In France this has happened repeatedly, and every one familiar with French naval literature knows how strong has been the expression of opinion by competent writers in regard to the evil effects 'of continual changes of policy. The debates on current French Navy Estimates since M. Thomson has become Min- ister of Marine have illustrated and condemned afresh the proceedings of amateurs in naval design, whose political position enabled them to suspend or to radically change schemes which were in process of execution. Fortunately . we have not suffered in a similar way as yet, and it may be hoped we never shall. The French defenses mobiles at naval ports associate tor- pedo-boats and destroyers with submarines, small armor- clads being used as supports. Statements made by the financial secretary to the admiralty in March last (during the debate on the navy estimates) indicate that the admiralty policy is in general agreement with French practice so far as the association of submarines and surface torpedo-vessels is concerned; but there was no mention of armored vessels being employed as supports. In speaking of submarines Mr. Prettyman said: They are able through their invisibility to do in the day exactly. what surface torpedo craft can do by night. 'The main, attribute of the latter is invisibility; that invisibility submarines attain by day. They have, of course, a very considerable moral effect upon an CHeMyN cee Vion may classify a submarine as a "daylight" torpedo boat of moderate speed and very considerable radius of action. - It is not a pres- ent condition, but it certainly may be looked upon as a possible condi- tion, that certain areas in war time, by the use of surface torpedo craft by night and submarines by day, may be practically denied to large ships. At present the only answer to them is that the other belligerent should be in a similar -position to deny these same waters to its enemy's ships. Therefore. the submarine in that particular is the only answer to the submarine. 'There is one other immediate and very important function of the submarine, and that is the defense of our ports, harbors and coast. That is the most important point. It is quite clear that the use of the submarine expands the range of the defense far beyond the guns of the forts defending any harbor. 'These vessels will not only defend the ports but link up the defenses, and the possession of a sufficient number of them would greatly reduce the anxiety of any admiral entrusted with the defense of our coast. ; This official statement of the role to be assigned in the immediate future to British submarines obviously had been carefully considered, and action has since been taken in